Etymologically
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lucid

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Pronunciation

  • /ˈl(j)uːsɪd/[1]

Etymology

It is borrowed from Latin lūcidus (“light, bright, clear”),[2][3][4][5][6] perhaps through French lucide or Italian lucido;[7][8][9] Barnhart takes it both through Middle French and directly from Latin.[10] The Latin adjective is from lūceō (“to shine”), from lūx (“light”), with the suffix -idus,[3][6][8] from Proto-Indo-European *leuk- (“to shine, be bright”).[3][4] It is related to light, lucent, elucidate and pellucid.[11][10] The phrase lucid interval follows Medieval Latin lūcida intervalla, a plural common in medieval works on lunacy and in legal documents.[3][12]

Earliest recorded meaning

In lucid interval, a period of calm in the midst of confusion: 1581, in W. Allen's defence of the two English colleges.[2] On its own the adjective first meant "bright, shining", in Spenser's Prosopopoia (Mother Hubberds Tale, 1591).[2][10][5][3]

Semantic evolution

The literal sense "bright, shining" is now poetic or technical:[2][8] in entomology and botany lucid means smooth and shining, and in astronomy a lucid star is one visible to the naked eye.[2][8] Johnson (1755) gave "shining; bright; glittering" first, with a quotation from Milton.[13] From 1620 the word also meant "translucent, clear".[2] A lucid interval was, from 1603, a spell of sanity in a person with a mental illness.[2] From 1656 it was also an interval of sunshine in a storm, which the OED calls the etymological sense;[2] Etymonline thinks the image was probably that of a calm, clear spell during a storm.[3] The modern sense "clearly reasoned or expressed, easy to understand" is recorded from 1786,[2][10][3] and the use of people, "clear-headed, sane", from 1843, in Carlyle.[2] The noun lucidity followed the same path, from "brightness" in 1656 to intellectual clearness in 1851.[10]

Timeline

  • 1581 – lucid interval, a period of calm amid confusion.[2]
  • 1591 – bright, shining.[2][10][5]
  • 1603 – lucid interval, a period of sanity in a mental illness.[2]
  • 1620 – translucent, clear.[2]
  • 1640s – lucidness.[3]
  • 1656 – lucidity, brightness.[10]
  • 1786 – clear in reasoning or expression, easily understood.[2][10][3]
  • 1843 – of people, clear-headed, sane.[2]

Meanings

Adjective

  1. Clearly expressed and easy to understand: a lucid account of the treaty.[14][5][4][2]
  2. Able to think clearly; rational or sane, especially between periods of confusion: The patient was lucid for a few hours each morning.[4][5][14][2]
  3. (poetic) Bright, shining, luminous.[4][14][2][8]
  4. Clear, translucent.[4][2][8]
  5. (astronomy) Of a star, visible to the naked eye.[2][8]
  6. (entomology, botany) Smooth and shining.[2][8]

Word family

  • lucidity
  • lucidly
  • lucidness
  • nonlucid
  • unlucid
  • elucidate
  • light
  • lucent
  • pellucid

References

  1. ^ Wiktionary, the free dictionary, https://en.wiktionary.org
  2. ^ a b c d e f g h i j k l m n o p q r s t u v Oxford English Dictionary Online (accessed March 2026), Oxford: Oxford University Press
  3. ^ a b c d e f g h i Harper, Douglas. Online Etymology Dictionary, https://www.etymonline.com
  4. ^ a b c d e f The American Heritage Dictionary of the English Language (online 2024), 5th ed., Boston: Houghton Mifflin Harcourt
  5. ^ a b c d e Merriam-Webster Unabridged Dictionary (2024), online ed., Springfield, Mass.: Merriam-Webster
  6. ^ a b Dictionary.com Unabridged (2016), based on the Random House Unabridged Dictionary, New York: Random House
  7. ^ Stevenson, Angus, ed. (2010), Oxford Dictionary of English, 3rd ed., Oxford: Oxford University Press
  8. ^ a b c d e f g h Shorter Oxford English Dictionary on Historical Principles (2002), 5th ed., ed. William R. Trumble and Angus Stevenson, Oxford: Oxford University Press
  9. ^ Hoad, T. F., ed. (1986), The Concise Oxford Dictionary of English Etymology, Oxford: Clarendon Press
  10. ^ a b c d e f g h Barnhart, Robert K. (1988), The Barnhart Dictionary of Etymology
  11. ^ Klein, Ernest. A Comprehensive Etymological Dictionary of the English Language. 2 vols. Amsterdam: Elsevier, 1966–1967.
  12. ^ Weekley, Ernest (1921), An Etymological Dictionary of Modern English, London: John Murray
  13. ^ Johnson, Samuel (1755), A Dictionary of the English Language, London; 4th ed. 1773; Johnson's Dictionary Online, ed. Beth Rapp Young et al.
  14. ^ a b c Collins English Dictionary (2023), Glasgow: HarperCollins